Effect of pre-straining treatment on high temperature creep behavior of Ni-based single crystal superalloys

Haibo Long, Shengcheng Mao, Yinong Liu, Hua Wei, Qingsong Deng, Yanhui Chen, Ze Zhang, Xiaodong Han

    Research output: Contribution to journalArticle

    7 Citations (Scopus)

    Abstract

    This study investigated a novel hypothesis on the influences of residual or pre-dislocation structures on creep life of Ni-based single crystal superalloys. Different types of anisotropic dislocation structures were created by pre-straining the samples at a relatively low temperature under different constant bias load conditions. After such pre-straining treatment, the samples were subjected to creep testing at higher temperatures under uniaxial tension. It was found that the pre-straining treatment was effective in creating different anisotropic dislocation structures without affecting the γ′ phase cuboid morphology and that the samples containing different anisotropic dislocation structures have all significantly reduced creep lives. The difference in the anisotropy of the dislocation structures has little influence on the reduction of the creep life or the rafting morphology of the γ′ phase cuboids. By using a Re-free alloy, the influence of the TCP phase precipitation on creep life is also clarified. These observations suggest that interruption to high temperature straining is the main contributor to the reduced creep lives. This finding raises a serious concern on the validity, or reliability, of creep life assessment based on continuous laboratory creep tests for real life applications, where the services are almost always interrupted into intermittent sessions.

    Original languageEnglish
    Article number107633
    JournalMaterials and Design
    Volume167
    DOIs
    Publication statusPublished - 5 Apr 2019

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